The present invention concerns a means of reinforcing concrete. More particularly, the invention concerns a reinforcement means which is arranged to extend upwards from the upper face of a cast wall past the predetermined surface of the joisting slab to be cast on top of the wall. The reinforcement means is primarily intended to serve as a so called safety reinforcement for the wall to be subsequently cast on top of the first-mentioned wall in order to eliminate the risk of collapse of the wall below.
In accordance with conventional techniques rigid reinforcement rods are used which thus project somewhat upwards above the cast slab forming the floor joisting. These projecting ends of the reinforcement rods are a hindrance in several respects. In the surface treatment of the joisting slab such as vibration, scouring and smoothing, the rod ends are in the way. For example, a vibro tube which has the form of an elongate body which normally extends across the entire slab, must be lifted over the rod ends, one man lifting each end of the vibro tube, which is a demanding task. Because of the rod ends it is not either possible to satisfactorily treat the marginal areas on either side of the row of reinforcement rods. In addition, this row of reinforcement rods on the whole hampers the building worker in his job and constitutes a constant risk of injury to the worker in that he easily gets caught by a rod or trips and falls against the rigid rod ends.
For this reason the elimination of the risks and inconveniences involved with the projecting rigid reinforcement rod ends has been urgent. In accordance with one solution a novel reinforcement method has been developed. In accordance with this method the reinforcement rods which project upwards from a cast wall are allowed to project only up to a height which is somewhat below the predetermined level of the joisting slab to be cast on top of said wall. Onto the free ends of the reinforcement rods are then threaded a block of cellular plastics, preferably Frigolit. The joisting slab is then cast, whereby the block of cellular plastics will be enclosed in the cast slab. However, care is taken that the upper surface of the blocks will be essentially level with the upper surface of the slab. As in this case there will be no projecting ends the surface treatment of the slab may be performed in a much more rapid and safer way while at the same time the entire surface of the slab will be treated with equally good results. When the treatment of the slab is finished, the blocks of cellular plastics are dissolved with the use of washing thinner, whereby a cavity is formed in the slab about the rod ends which thus are exposed. A conical sleeve of a special design is threaded onto one end of a loose reinforcement rod and together they are threaded onto an exposed rod end in the slab, whereupon the conical sleeve is hammered on by means of a tool so as to wedge the rod ends securely inside the sleeve. A secure joint between two reinforcement rods in two separate walls is thus formed.
Although the method described above provides the advantages outlined in the aforegoing in facilitating the surface treatment of the joisting slab it still involves several complications. The reinforcement work becomes involved and complicated on account of the numerous working operations, which means loss of time. In order to achieve a strong joint between the reinforcement rods in separate floors it is necessary that the jointing be performed with great care. This is not always done in practice where rapidity of work often prevails over exactness. Bad execution of the reinforcement joints means that the reinforcement as a whole becomes inferior.